Add support of multi-dim C-style array.

* Support up to 4 dimensional array.
nlohmann · Jan 6, 2024 · 68c0097 · 68c0097
1 parent a259ecc
commit 68c0097
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diff --git a/include/nlohmann/detail/conversions/from_json.hpp b/include/nlohmann/detail/conversions/from_json.hpp
@@ -190,6 +190,54 @@ auto from_json(const BasicJsonType& j, T (&arr)[N])  // NOLINT(cppcoreguidelines
     }
 }
 
+template<typename BasicJsonType, typename T, std::size_t N1, std::size_t N2>
+auto from_json(const BasicJsonType& j, T (&arr)[N1][N2])  // NOLINT(cppcoreguidelines-avoid-c-arrays,hicpp-avoid-c-arrays,modernize-avoid-c-arrays)
+-> decltype(j.template get<T>(), void())
+{
+    for (std::size_t i1 = 0; i1 < N1; ++i1)
+    {
+        for (std::size_t i2 = 0; i2 < N2; ++i2)
+        {
+            arr[i1][i2] = j.at(i1).at(i2).template get<T>();
+        }
+    }
+}
+
+template<typename BasicJsonType, typename T, std::size_t N1, std::size_t N2, std::size_t N3>
+auto from_json(const BasicJsonType& j, T (&arr)[N1][N2][N3])  // NOLINT(cppcoreguidelines-avoid-c-arrays,hicpp-avoid-c-arrays,modernize-avoid-c-arrays)
+-> decltype(j.template get<T>(), void())
+{
+    for (std::size_t i1 = 0; i1 < N1; ++i1)
+    {
+        for (std::size_t i2 = 0; i2 < N2; ++i2)
+        {
+            for (std::size_t i3 = 0; i3 < N3; ++i3)
+            {
+                arr[i1][i2][i3] = j.at(i1).at(i2).at(i3).template get<T>();
+            }
+        }
+    }
+}
+
+template<typename BasicJsonType, typename T, std::size_t N1, std::size_t N2, std::size_t N3, std::size_t N4>
+auto from_json(const BasicJsonType& j, T (&arr)[N1][N2][N3][N4])  // NOLINT(cppcoreguidelines-avoid-c-arrays,hicpp-avoid-c-arrays,modernize-avoid-c-arrays)
+-> decltype(j.template get<T>(), void())
+{
+    for (std::size_t i1 = 0; i1 < N1; ++i1)
+    {
+        for (std::size_t i2 = 0; i2 < N2; ++i2)
+        {
+            for (std::size_t i3 = 0; i3 < N3; ++i3)
+            {
+                for (std::size_t i4 = 0; i4 < N4; ++i4)
+                {
+                    arr[i1][i2][i3][i4] = j.at(i1).at(i2).at(i3).at(i4).template get<T>();
+                }
+            }
+        }
+    }
+}
+
 template<typename BasicJsonType>
 inline void from_json_array_impl(const BasicJsonType& j, typename BasicJsonType::array_t& arr, priority_tag<3> /*unused*/)
 {

diff --git a/single_include/nlohmann/json.hpp b/single_include/nlohmann/json.hpp
@@ -4817,6 +4817,54 @@ auto from_json(const BasicJsonType& j, T (&arr)[N])  // NOLINT(cppcoreguidelines
     }
 }
 
+template<typename BasicJsonType, typename T, std::size_t N1, std::size_t N2>
+auto from_json(const BasicJsonType& j, T (&arr)[N1][N2])  // NOLINT(cppcoreguidelines-avoid-c-arrays,hicpp-avoid-c-arrays,modernize-avoid-c-arrays)
+-> decltype(j.template get<T>(), void())
+{
+    for (std::size_t i1 = 0; i1 < N1; ++i1)
+    {
+        for (std::size_t i2 = 0; i2 < N2; ++i2)
+        {
+            arr[i1][i2] = j.at(i1).at(i2).template get<T>();
+        }
+    }
+}
+
+template<typename BasicJsonType, typename T, std::size_t N1, std::size_t N2, std::size_t N3>
+auto from_json(const BasicJsonType& j, T (&arr)[N1][N2][N3])  // NOLINT(cppcoreguidelines-avoid-c-arrays,hicpp-avoid-c-arrays,modernize-avoid-c-arrays)
+-> decltype(j.template get<T>(), void())
+{
+    for (std::size_t i1 = 0; i1 < N1; ++i1)
+    {
+        for (std::size_t i2 = 0; i2 < N2; ++i2)
+        {
+            for (std::size_t i3 = 0; i3 < N3; ++i3)
+            {
+                arr[i1][i2][i3] = j.at(i1).at(i2).at(i3).template get<T>();
+            }
+        }
+    }
+}
+
+template<typename BasicJsonType, typename T, std::size_t N1, std::size_t N2, std::size_t N3, std::size_t N4>
+auto from_json(const BasicJsonType& j, T (&arr)[N1][N2][N3][N4])  // NOLINT(cppcoreguidelines-avoid-c-arrays,hicpp-avoid-c-arrays,modernize-avoid-c-arrays)
+-> decltype(j.template get<T>(), void())
+{
+    for (std::size_t i1 = 0; i1 < N1; ++i1)
+    {
+        for (std::size_t i2 = 0; i2 < N2; ++i2)
+        {
+            for (std::size_t i3 = 0; i3 < N3; ++i3)
+            {
+                for (std::size_t i4 = 0; i4 < N4; ++i4)
+                {
+                    arr[i1][i2][i3][i4] = j.at(i1).at(i2).at(i3).at(i4).template get<T>();
+                }
+            }
+        }
+    }
+}
+
 template<typename BasicJsonType>
 inline void from_json_array_impl(const BasicJsonType& j, typename BasicJsonType::array_t& arr, priority_tag<3> /*unused*/)
 {

diff --git a/tests/src/unit-conversions.cpp b/tests/src/unit-conversions.cpp
@@ -344,6 +344,64 @@ TEST_CASE("value conversion")
             CHECK(std::equal(std::begin(nbs), std::end(nbs), std::begin(nbs2)));
         }
 
+        SECTION("built-in arrays: 2D")
+        {
+            const int nbs[][3] = {{0, 1, 2}, {3, 4, 5}}; // NOLINT(cppcoreguidelines-avoid-c-arrays,hicpp-avoid-c-arrays,modernize-avoid-c-arrays)
+            int nbs2[][3] = {{0, 0, 0}, {0, 0, 0}}; // NOLINT(cppcoreguidelines-avoid-c-arrays,hicpp-avoid-c-arrays,modernize-avoid-c-arrays)
+
+            const json j2 = nbs;
+            j2.get_to(nbs2);
+            CHECK(std::equal(std::begin(nbs[0]), std::end(nbs[1]), std::begin(nbs2[0])));
+        }
+
+        SECTION("built-in arrays: 3D")
+        {
+            const int nbs[][2][3] = {\
+                {{0, 1, 2}, {3, 4, 5}}, \
+                {{10, 11, 12}, {13, 14, 15}}\
+            }; // NOLINT(cppcoreguidelines-avoid-c-arrays,hicpp-avoid-c-arrays,modernize-avoid-c-arrays)
+            int nbs2[][2][3] = {\
+                {{0, 0, 0}, {0, 0, 0}}, \
+                {{0, 0, 0}, {0, 0, 0}}\
+            }; // NOLINT(cppcoreguidelines-avoid-c-arrays,hicpp-avoid-c-arrays,modernize-avoid-c-arrays)
+
+            const json j2 = nbs;
+            j2.get_to(nbs2);
+            CHECK(std::equal(std::begin(nbs[0][0]), std::end(nbs[1][1]), std::begin(nbs2[0][0])));
+        }
+
+        SECTION("built-in arrays: 4D")
+        {
+            const int nbs[][2][2][3] = {\
+                {
+                    \
+                    {{0, 1, 2}, {3, 4, 5}}, \
+                    {{10, 11, 12}, {13, 14, 15}}\
+                }, \
+                {
+                    \
+                    {{20, 21, 22}, {23, 24, 25}}, \
+                    {{30, 31, 32}, {33, 34, 35}}\
+                }\
+            }; // NOLINT(cppcoreguidelines-avoid-c-arrays,hicpp-avoid-c-arrays,modernize-avoid-c-arrays)
+            int nbs2[][2][2][3] = {\
+                {
+                    \
+                    {{0, 0, 0}, {0, 0, 0}}, \
+                    {{0, 0, 0}, {0, 0, 0}}\
+                }, \
+                {
+                    \
+                    {{0, 0, 0}, {0, 0, 0}}, \
+                    {{0, 0, 0}, {0, 0, 0}}\
+                }\
+            }; // NOLINT(cppcoreguidelines-avoid-c-arrays,hicpp-avoid-c-arrays,modernize-avoid-c-arrays)
+
+            const json j2 = nbs;
+            j2.get_to(nbs2);
+            CHECK(std::equal(std::begin(nbs[0][0][0]), std::end(nbs[1][1][1]), std::begin(nbs2[0][0][0])));
+        }
+
         SECTION("std::deque<json>")
         {
             std::deque<json> a{"previous", "value"};